Machines for removing refractory linings from blast furnace stacks and the like or for removing slag from soaking pits generally comprise a superstructure from which a boom is suspended for swinging about a vertical axis and for pivotal adjustment about a horizontal axis to raise and lower the tip thereof which swingably adjustably carries an air hammer having a moil or chisel point to break up the refractory lining or slag as the case may be. In the case of the lining removing machine, the superstructure is progessively lowered into the blast furnace stack as the lining removal operation progesses and in the case of a soaking pit clean-out machine, the superstructure has tracks which support the boom carrying trolley for longitudinal movement from one end to the other of the soaking pit as the clean-out operation progesses.
As evident, machines of the character indicated must be transported to and set up at the location of the blast furnace stack or soaking pit, and the lining removal or slag clean-out operation is obscured by the superstructure from which the boom and hammer assembly are suspended for swinging about vertical and horizontal axes.